Figure 1. Anteroposterior radiograph of right ankle. Credit: Dagan Cloutier, MPAS, PA-C
Figure 2. Lateral view of ankle. Credit: Dagan Cloutier, MPAS, PA-C
Figure 3. Sagittal MRI of right ankle showing edema. Credit: Dagan Cloutier, MPAS, PA-C
A 38-year-old woman presents with right ankle pain that began a year ago. The patient denies any known injury or precipitating event that caused the pain. The patient underwent brain surgery for the treatment of a brain tumor 2 years ago; she was treated with high-dose corticosteroids for over 4 months after surgery. On physical examination, the ankle has no abnormalities and mild generalized pain is found with range of motion at the talus. Radiographs are taken (Figures 1 and 2) and show no abnormalities of the ankle. Sagittal magnetic resonance imaging (MRI, Figure 3) shows edema in the talus consistent with avascular necrosis. No signs of collapse of the ankle joint are found and the avascular changes appear to be more in the head of the talus.
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Steroid-induced osteonecrosis is a condition that occurs in patients on long-term systemic corticosteroid therapy. The exact pathophysiology is unclear, however, steroids can disrupt the blood supply to bone leading to bone matrix and articular cartilage degeneration.1 Steroid-induced osteonecrosis accounts for 10% of all total joint replacements performed annually in the United States.1 The most common location of osteonecrosis is the hips; occurrence in the talus is rare. Higher dosage of steroids and longer treatment duration increases the risk of developing osteonecrosis.1,2
Most patients with early disease (no talar collapse) are treated conservatively with a period of nonweight-bearing (up to 3-6 months in some cases), in theory, to help revascularize the talus.2 Bracing and extracorporeal shock wave therapy have been used to help revascularize the talus if conservative treatments fail. Surgical procedures such as core decompression and bone grafting have been used to salvage the talus before a larger procedure such as a fusion and talus replacement is needed.2
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor in chief of the Journal of Orthopedics for Physician Assistants.
1. Powell C, Chang C, Naguwa SM, Cheema G, Gershwin ME. Steroid induced osteonecrosis: an analysis of steroid dosing risk. Autoimmun Rev. 2010;9(11):721-743. doi:10.1016/j.autrev.2010.06.007
2. Gross CE, Haughom B, Chahal J, Holmes GB Jr. Treatments for avascular necrosis of the talus: a systematic review. Foot Ankle Spec. 2014;7(5):387-397. doi:10.1177/1938640014521831